Add optimization for Contact Form 7

Onload load Contact Form 7’s JavaScript if a form is present on the page.

inc/Plugin.php

@@ -378,6 +378,7 @@ private function init_common_subscribers() {
 			'translatepress',
 			'themify',
 			'wpgeotargeting',
+			'contactform7',
 			'lazyload_css_subscriber',
 			'shoptimizer',
 		];

inc/ThirdParty/Plugins/ContactForm7.php

@@ -0,0 +1,28 @@
+<?php
+namespace WP_Rocket\ThirdParty\Plugins;
+
+use WP_Rocket\Event_Management\Subscriber_Interface;
+
+class ContactForm7 implements Subscriber_Interface {
+	/**
+	 * Subscribed events.
+	 */
+	public static function get_subscribed_events() {
+		return [
+			'wp' => [ 'maybe_optimize_contact_form_7', 10 ],
+		];
+	}
+
+	/**
+	 * Optimize ContactForm7 scripts.
+	 *
+	 * @return array
+	 */
+	public function maybe_optimize_contact_form_7() {
+		if ( defined( 'WPCF7_LOAD_JS' ) && WPCF7_LOAD_JS && ! has_action( 'wpcf7_shortcode_callback' ) ) {
+			// Only load the frontend scripts on the new 'wpcf7_shortcode_callback' hook.
+			add_filter( 'wpcf7_load_js', '__return_false' );
+			add_action( 'wpcf7_shortcode_callback', 'wpcf7_enqueue_scripts' );
+		}
+	}
+}

inc/ThirdParty/ServiceProvider.php

@@ -36,6 +36,7 @@
 use WP_Rocket\ThirdParty\Plugins\CDN\{Cloudflare,CloudflareFacade};
 use WP_Rocket\ThirdParty\Plugins\Jetpack;
 use WP_Rocket\ThirdParty\Plugins\WPGeotargeting;
+use WP_Rocket\ThirdParty\Plugins\ContactForm7;
 use WP_Rocket\ThirdParty\Plugins\SEO\RankMathSEO;
 use WP_Rocket\ThirdParty\Plugins\SEO\AllInOneSEOPack;
 use WP_Rocket\ThirdParty\Plugins\SEO\SEOPress;
@@ -101,6 +102,7 @@ class ServiceProvider extends AbstractServiceProvider {
 		'rapidload',
 		'translatepress',
 		'wpgeotargeting',
+		'contactform7'
 	];
 
 	/**
@@ -257,5 +259,6 @@ public function register() {
 			->share( 'rapidload', RapidLoad::class );
 		$this->getContainer()->share( 'translatepress', TranslatePress::class );
 		$this->getContainer()->share( 'wpgeotargeting', WPGeotargeting::class );
+		$this->getContainer()->share( 'contactform7', ContactForm7::class );
 	}
 }